


Like brothers do

by theodora_honey



Category: Free!
Genre: A little bit anyway, Dry Humping, First Time, Guilt, Hand Jobs, Incest, M/M, Praise Kink, Sibling Incest, ages are ambiguous, anyway who watches free for the plot am i right, based heavily on their free starting days dynamic, but tbh they're probably both underage, heed the incest tag seriously it's heavy, it's consensual tho, maybe they're in america, this is pure smut with a sprinkle of plot, who knows where in the timeline this takes place, woops i got confused and had to fix that tag lol
Language: English
Status: Completed
Published: 2018-07-28
Updated: 2018-07-28
Packaged: 2019-06-17 13:03:16
Rating: Explicit
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 1
Words: 7,069
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/15461973
Author URL: https://archiveofourown.org/users/theodora_honey/pseuds/theodora_honey
Summary: The mere thought of Ikuya being someone else’s little brother filled him with indescribable jealousy, even if it meant he was free to pursue him. No, it was because Ikuya was Natsuya’s brother that he was so attracted to him. As disgusting as that was, it was the truth. The thought filled him with equal parts revulsion and arousal, brewing in his stomach like a twisted love potion. It was addictive.Years ago, Natsuya pushed Ikuya away to keep him safe, shielding his best friend and brother from the filthy, abhorrent feelings he couldn't stop himself from thinking. But Ikuya is desperate to restore the closeness of their relationship, even (or especially) if it means taking it to completely new heights.





	Like brothers do

**Author's Note:**

> Y'all probably know but aniki = big brother (what Ikuya calls Natsuya in Free! Starting Days).
> 
> Enjoy >:3c

“Be good for your big brother, Ikuya,”

“Yeah, yeah,”

“And Natsuya, you’re the eldest, so you have to take responsibility. Look after your little brother, okay?”

“I will, Mom. You don’t need to worry.”

“We’ll see you two on Sunday, then. Bye-bye, good luck!”

“Have a good trip!”

Natsuya smiled and waved as his parents loaded their bags into the car and made their way down the drive, not turning back to the house until they were out of sight. His little brother didn’t stick around to see them off, already flopped on the sofa with his earphones in by the time the engine had started.

Natsuya stopped in the doorway to look at him a moment, an indulgence he didn’t allow himself very often these days. Ikuya’s small, lithe frame was draped haphazardly over the furniture, one arm up behind his head and the other resting lazily on his stomach, one leg dangling down to the floor. His closed eyes showed off long, sweetly curled eyelashes, and the slight pout that had taken up near-permanent residence on his mouth only made his lips look soft and full. It was unfair, Natsuya thought for the thousandth time. Unfair that his brother could be so cute, make him feel giddy, like his feet never quite reached the ground and his insides were fizzing like sherbet powder. Unfair that he would be taunted by Ikuya for the rest of his life and never be able to do anything about it. Unfair that he had to hurt him by pushing him away, just to keep him safe from the awful truth.

But still, he wouldn’t change a thing even if he could. The mere thought of Ikuya being someone else’s little brother filled him with indescribable jealousy, even if it meant he was free to pursue him. No, it was _because_ Ikuya was Natsuya’s brother that he was so attracted to him. As disgusting as that was, it was the truth. The thought filled him with equal parts revulsion and arousal, brewing in his stomach like a twisted love potion. It was addictive.

And now they were going to be on their own for five days while their parents visited relatives. It wouldn’t be a problem, it wasn’t going to change his behaviour at all, he promised himself that. It just made his intrusive thoughts even stronger. He wasn’t going to touch Ikuya, but if he _ever was,_ now would be the time to do it. With their parents gone, he might just be able to get away with it. But that didn’t matter, because he wasn’t going to, no matter what. He still loved his little brother, before all else. He would never hurt him like that.

Unfortunately, his determination didn’t help him think about it any less.

Ikuya opened his eyes and looked over at Natsuya, shooting him an irritated frown as he realized he was being stared at. “What?” he grunted.

“Nothing,” Natsuya replied with an irritated frown. As much as he adored Ikuya, he wasn’t a fan of the bratty attitude he’d picked up in the last couple of years. Although, he supposed he only had himself to blame for that - Ikuya had never really recovered from when Natsuya pushed him away. If only he could understand that it was for his own good. “I was just thinking about what to make for dinner. What do you feel like?”

“I don’t care,” Ikuya said, turning on the sofa so that his back faced Natsuya. “Make whatever.”

“Hey, I’m not doing it all myself. You’ve got to help out, too.”

“Aren’t you the older brother?” Ikuya replied, voice flat and disinterested. “It’s your job.”

“Hey, Ikuya, you can’t --” Natsuya started, but he gave up with a sigh. There was no point arguing with his brother when he was in a mood like this. “Fine. I’ll cook tonight, but you’re going to help tomorrow.”

Ikuya only shrugged in reply.

Dinner was a simple omurice - Natsuya decided not to cook anything more exciting on principle. Ikuya slumped down at the dining table, murmured a weak ‘itadakimasu’, and started spooning the food into his mouth without so much as a glance at Natsuya. They ate in silence, and Natsuya found himself staring at his little brother again, this time out of annoyance rather than attraction. Ikuya’s attitude had been worse than usual the last couple of days, and he seemed to have worked himself up into a particularly bad mood tonight. It was just about enough to turn Natsuya off of him completely.

Ikuya finished off his plate and took it to the sink. “Thanks for dinner,” he said dully, still not looking at Natsuya. “I’m gonna go to bed early.”

“Ikuya,” Natsuya growled, feeling his frustration boil over the edge. “What’s with you today? I cook for you when you refuse to help out, and you can’t even thank me properly? The least you could do is wash up afterwards.”

“I don’t care about that,” Ikuya mumbled as he walked past.

The screeching sound of a chair being pushed against the wooden floor filled the room as Natsuya stood up and grabbed his brother by the wrist. “Hey, Ikuya!”

Ikuya tried to yank his hand back, but Natsuya kept his grip firm. “What?!” he snarled, looking up at Natsuya with fierce eyes. “Can’t you just leave me alone? Why do you care all of a sudden?”

“I care when you’re acting like a spoiled brat,” Natsuya said. “What’s your problem? You think that as soon as Mom and Dad leave you get to act like you own the place?”

“I don’t think that,” Ikuya said, pushing on Natsuya’s chest with one hand as he tried to free his other. Natsuya only grabbed that one by the wrist, too.

“Then what?” Natsuya growled.

“Let go!” Ikuya demanded, squirming in Natsuya’s grasp.

“No,” Natsuya replied, tightening his grip and pushing Ikuya back towards the wall. “Not until you tell me why you’re acting like this.”

“You don’t understand!” Ikuya yelled, his voice suddenly loud and bursting with emotion. “You don’t understand me at all, aniki! Just leave me alone!”

Natsuya saw angry tears start to form in Ikuya’s eyes and let go of his wrists, suddenly filled with guilt.

To his surprise, Ikuya didn’t bolt as soon as he was freed. He turned his shoulder on Natsuya and wiped at his eyes with his sleeve, rubbing a hand over his one wrist, his face burning red with unshed tears.

“Ikuya… I’m sorry,” Natsuya said. His hand twitched as he fought back the instinct to reach out and touch him, turn his chin so that he would be forced to look him in the eyes. “You’re right, I don’t know what’s going on. But we can talk about it, if you’d like.”

“No,” Ikuya spat bitterly. “We can’t.”

“Why not?” he asked, and when Ikuya said nothing in response he realized how stupid a question it was. It was his own fault Ikuya couldn’t be open with him anymore. “Well… if you change your mind…” Natsuya said, feeling completely inadequate. He felt terrible for assuming Ikuya was just in a bad mood - he could see now that something deeper was hurting him tonight. He wished he could make it better, but he had forfeited that right when he pushed Ikuya away and built a wall between them.

“Yeah, whatever,” Ikuya mumbled, and he ran up the stairs and to his bedroom. His door swung shut with a slam as Natsuya stood in the dining room, his face in his hands.

***

Believing it best that he leave his brother alone for the night, Natsuya washed up the dinner dishes and retired to his room to get some homework done. He found himself easily distracted, though. His bedroom bordered Ikuya’s and every thud of his footsteps and creak of his desk chair caught his attention through the thin wall, making him think back on their fight earlier - the tears in Ikuya’s eyes, the betrayal in his voice. _You don’t understand me at all, aniki._ It was an accusation that cut right to Natsuya’s heart. Natsuya had believed that even if he couldn’t allow himself to be close to his brother, at least he still understood him, at least he could still observe him from a distance and be satisfied with that. But Ikuya was right, Natsuya didn’t understand him anymore. There were layers to Ikuya that he had buried so deep and hidden so well that Natsuya hadn’t even noticed. Or if he had, he had contributed it to regular teenage angst instead of seeing it for what it was -- whatever that might be. He wanted desperately to understand Ikuya, but he didn’t, and it was his own fault. As a result, Ikuya was hurting.

He heard Ikuya leave his room and moments later, the sound of running water in the bathroom. Gripping his pencil tight, Natsuya cursed himself as his mind drifted against his will to thoughts of Ikuya stripping his clothes and stepping into the stream of hot water, running soapy hands over his body and through his hair, shoulders dropping as he warmed and relaxed. _God damn it,_ he didn’t need to be thinking about this tonight, but a primal corner of his brain that he couldn’t switch off was still insisting that he strike while he had the chance. It didn’t help that Natsuya knew the shape of Ikuya’s body all too well, having watched the way he moved through the water with hypnotizing grace, the way his muscles strained as he stretched before a swim, the way his hair plastered to his neck when wet, the way he seemed to glow when light bounced off the water trailing down his lean frame and beaded against his pale skin. Natsuya’s eyes had traced and memorized every inch of Ikuya’s near-naked body, and now if he just leaned back and closed his eyes, he could see him in front of him as clear as day.

_Fuck._ Deep, intense arousal had been needling at him since the days leading up to his parent’s departure, but it was only getting worse. Even after a fight and the guilt that followed it, Natsuya still couldn’t keep these disgusting thoughts from his head. He was angry with himself, but tried to reason that he shouldn’t be all that surprised. Guilt was a feeling so heavily associated with his attraction to Ikuya that it was pretty much a conditioned response at this point. Start feeling guilty, start thinking back to memories of reaching under his clothes and stroking his fingers over himself with Ikuya’s name on his lips. Guilt, arousal, disgust, self-loathing, the ecstasy of climax - these were feelings that were tangled deep and inseparable inside him. He ran a trembling hand over his chest and gasped when his fingers brushed his nipple, the intensity of the arousal that jolted through him making him bend over his desk.

Flattening his palms on the surface in front of him, he squeezed his thighs as tight as he could to try to keep blood from flowing to his erection. He wouldn’t do this. He had already hurt Ikuya enough, he wouldn’t betray him again tonight by jerking off to the thought of him with nothing but a thin wall between them. Taking a deep, shaking breath, he gathered himself and his attention back to his homework sheet.

His efforts to concentrate were in vein, however. Natsuya heard the shower switch off and then a soft sigh as Ikuya settled into the bath with a slosh. The walls were really too thin - Natsuya could hear every drop of water as Ikuya scooped it up and let it run through his fingers, every movement Ikuya made as he slid against the acrylic tub. His heart hammered against his ribcage as he remembered the feeling of Ikuya’s body, wet and slippery against his own as they swam together as kids, playfully pushing each other down or grabbing onto each other’s waists and towing one another around like a tugboat. It had been years since they had played like that, but Natsuya still clearly remembered how good it felt to wrap his hands around Ikuya’s slim body, feel his silky skin under his fingertips, feel his chest pressed flush against Natsuya’s own, his arms thrown over his shoulders and his legs wrapped around his waist as Natsuya carried him around, feel him squirm with laughter as he was tickled and pulled under the surface. Once Natsuya had figured out just why it felt so good he had put a stop to it, of course, but the memory was still there, and right now it was proving very difficult not to think back on as he pictured Ikuya in the bathtub just one room away.

He wanted to go in there and run his hands all over Ikuya’s body, pull him open not just physically but emotionally, peel back his layers and expose his core, get his tongue and fingers inside of him, bring his vulnerabilities and his tears to the surface and lick them away, swallow him down, cradle him in so close that their bodies became one and there was no chance Natsuya would never misunderstand him again.

He stood up suddenly, chest heaving with laboured breaths and his whole body trembling. He had to get out of here.

“I’m just going out for a quick jog,” he yelled outside the bathroom door, not waiting for a reply before he bolted down the stairs. He heard Ikuya yell a slightly confused ‘okay’ in reply as he slipped his shoes on and shut the door behind him.

The night air was brisk, a welcome change from the stifling atmosphere of his bedroom. _Get a hold of yourself,_ he berated himself. _He’s your brother. Nothing is going to happen tonight._ The exercise thankfully cleared his head, and after 10 minutes of running around the block, Natsuya felt composed enough to head back.

“I’m home,” he called to no one as he stepped inside, locking the door behind him. He slipped his shoes off and made his way upstairs.

Ikuya’s voice called out to him as he passed by his bedroom door. “I left the water for you.”

Natsuya stopped and smiled slightly. Ikuya might not be ready to come out of his room yet, but at least he wasn’t still angry enough to be ignoring Natsuya completely. “Thanks.”

He washed the dirt and sweat off his body in the shower, then settled into the bath, adding a little more hot water to get the temperature comfortable. Sighing and closing his eyes, he leaned his head back on the tub and thought. That bout of intense arousal seemed to have been overcome for now, but he’d have to be more careful in the future. Maybe it would be best if Ikuya stayed in whatever mood this was and kept to himself, at least until their parents got back. The less he saw Ikuya over the next few days, the easier it would be. He didn’t want to start another fight with him, either, especially when Ikuya was already feeling vulnerable, and Natsuya’s sexual frustration was probably only adding to his short temper. Maybe he should pay Nao a visit tomorrow, see if that would help.

Back in his room, he dried off his hair and changed into clean underwear before settling into bed. He wasn’t quite tired yet but he felt too drained to do any more homework, so he turned the lights off and started browsing through his phone. Memes and animal videos would be enough to keep him mostly distracted until he felt drowsy enough to fall asleep.

He could hear Ikuya in the room next door, muttering something indistinguishable to himself. Probably practicing for a school presentation or something, Natsuya figured. When he heard the bedroom door open and footsteps in the hall he assumed Ikuya needed to use the bathroom, but his heart jumped a beat when he the footsteps came to a halt outside his own door.

Everything was quiet for a few moments, and Natsuya waited with bated breath for Ikuya to do _something,_ though he had no idea what. The silence drew out so long that he had just about convinced himself he was imagining things, when a knock sounded softly at his door.

“Aniki,” Ikuya said, voice quiet and uncertain.

Natsuya stomach tied in knots so strong that it hurt. He swallowed and took a couple of breaths before replying. “Come in, Ikuya.”

Ikuya opened the door and stepped just inside, holding his arms in close to his sides and looking embarrassed and uncomfortable. He was wearing just his underwear and a loosely fitting tee - one that, with a thud of his heartbeat, Natsuya recognized as an old hand-me-down of his. He hadn’t seen Ikuya wear any of his old clothes before; he hadn’t realized he was using them to sleep in. _Fuck._

He sat up on his bed and waited for Ikuya to say something, give some indication of why he was there, but Ikuya remained silent, his eyes turned to the side and pointedly away from Natsuya.

“Are you okay?” Natsuya asked.

Ikuya nodded mutely, still staring intently at the wall to his right.

“Ehh…” Natsuya said, bewildered by what was going on. “Are you sure, Ikuya? Do you want to talk?”

Ikuya looked over and met his eyes, finally. He nodded. “Is -- If that’s okay…”

“Of course it is,” Natsuya replied.

Ikuya shut the door behind him and sat on the edge of Natsuya’s bed. It was dark, but enough light shone in from street lights outside the window that Natsuya could make out the nervous expression on Ikuya’s face, cheeks flushed red and lips trembling. Seeing him so flustered was doing terrible things to Natsuya. He urged his heart to stop beating so wildly.

“I wanted to apologize for before,” Ikuya said, hands in his laps and gaze following them. “I should have helped with dinner, or at least cleaned up. I shouldn’t have been so rude to you. I’m sorry.”

“It’s okay,” Natsuya said, managing to keep his voice steady. “That’s what big brothers are for, right?”

Ikuya gave a non committal hum but didn’t move from his spot on the bed, like he wanted to keep talking but didn’t know how.

“To be honest, I’ve noticed you’ve been a little on edge the last couple of days,” Natsuya said. “I mean, more than usual,” he added with a weak laugh, trying and failing to lighten up the atmosphere a little.

Ikuya sighed. “Sorry. And yeah, you’re right. I haven’t been feeling good.”

“What’s happened?” Natsuya asked.

“Nothing’s happened,” Ikuya said, squeezing his fists in frustration. “I’m just -- mmm -- it’s hard to -- ”

Ikuya suddenly flinched and his arm went up to cover his eyes, jaw clenched as he tried to hold back tears.

“Ikuya…” Natsuya said, reaching out to touch his hand to his younger brother’s back comfortingly. It was something he wouldn’t normally do, but seeing Ikuya so upset was overriding his usual no-touching policy.

“I just miss you, aniki, that’s all,” Ikuya said, his voice wet with tears as the words spilled out all at once. “With Mom and Dad gone I keep thinking that this should be a chance for us to spend more time together and have fun, but instead I can barely even talk to you and you still don’t want anything to do with me, and I don’t know what to do anymore. It hurts and it hasn’t stopped hurting and I _don’t know what to do_ . I wish we could go back to when we were kids and we were best friends and we didn’t hide anything from each other, you’d buy me ice cream and help me tie my shoelaces and let me sleep in your bed when I was scared and we’d swim together and it was fun. We had _fun_ and we were happy. I want to do all that again with you, but I can’t, and I don’t know what to do anymore. I just… I _miss_ you, aniki.”

Ikuya shuddered with barely-restrained sobs as Natsuya took his speech in. He already knew he had hurt Ikuya, of course, but it was still gut-wrenching to hear him spill it all out, crying and trembling and desperate for something to change.

Natsuya shifted down the bed and wrapped his arms around his brother from behind. “I’m so sorry, Ikuya. I never wanted to hurt you. Please believe that.”

Ikuya turned around and wrapped his arms around Natsuya’s waist, burying his head into the crook of his neck, and cried as Natsuya held him. Natsuya rubbed circles into the small of his back with one hand and stroked his hair with the other, teasing knots out of the soft, air-dried curls. He pressed his lips gently to Ikuya’s temple, hoping that his brother’s sobbing was enough to hide the fact that Natsuya’s heart was beating like it was trying to escape his body. It had been years since he had been close enough to Ikuya to smell the scent of his skin, and he had forgotten what it was like, but underneath a layer of the soap they shared was a scent unique to him, sweet and powdery and absolutely intoxicating. Natsuya took a deep, slow breath as discreetly as he could, filling his entire lungs until it overflowed into the rest of his body, sending feathery tingles down to his fingers and toes. He closed his eyes in bliss, vaguely aware that his behavior was horribly selfish but feeling too good to care, as if he was high on it.

After a few minutes, he slowly realized that Ikuya had stopped crying some time ago. He was breathing heavily into Natsuya’s neck, his fingers twitching slightly where they rested lightly on Natsuya’s lower back, feeling electric where he touched bare skin. Natsuya could feel the wetness of tears and the warmness of Ikuya’s breath tickling his neck, sending shivers down his spine. Ikuya’s whole body seemed to tremble in Natsuya’s arms, but Natsuya couldn’t be sure it wasn’t just his own body shaking. How long would Ikuya let him keep holding him like this? He certainly didn’t seem in any rush to stop, but Natsuya couldn’t afford to wait around and find out; heady, needful arousal, even stronger than earlier, was building up inside of him and he needed to get away from Ikuya’s touch and the smell of him before he did something he couldn’t take back.

He pulled back, helping Ikuya to sit upright, and looked down into his eyes. His pupils were blown wide in the low light, but his amber eyes still shone bright up at him, wet with leftover tears.

“Can we go back to how we used to be?” Ikuya asked, voice trembling and hopeful.

Natsuya licked his lips and swallowed. “I don’t know,” he answered truthfully, wiping his thumbs over Ikuya’s cheeks to brush tears away. Right now he could barely think of anything except how much he wanted to lean forward and kiss that inviting mouth, feel the softness of his lips and wetness of his tongue, hear him gasp and moan as he opened him up and pushed his way inside, violated him. He felt dizzy from how much he wanted it. But it couldn’t be further from what Ikuya wanted right now.

“Can I -- can I stay here the night, aniki? Like I used to?” Ikuya asked, staring up at him wide-eyed and innocent.

Natsuya’s brows snapped together in shock and he felt almost sick from the combination of desire and anxiety churning in his stomach, but he reeled himself in as he saw the earnestness in Ikuya’s eyes. He was just a miserable kid who needed kindness and reassurance from his big brother, who wanted to go back to a childhood source of comfort like a security blanket. He had no idea what it meant to Natsuya. And because of that, Natsuya had to refuse him, had to stand by his decision to keep that distance between them. It was for Ikuya’s own good.

But looking down into Ikuya’s open, helpless face, he found he couldn’t get the words out. Before he realized it, he was nodding. “Yeah,” he said, like he had lost control of his body and was watching someone else speak through his mouth. “Yeah, okay.”

Ikuya smiled, a rare and beautiful thing that made Natsuya’s chest ache. “Thank you, aniki.”

They lay down side by side, facing each other, and Natsuya pulled the covers over the two of them. It was a small bed, so Natsuya planned on sticking as close to one side as possible in order to give Ikuya space, but that plan was thwarted when Ikuya shuffled in closer to him and tucked his head down into Natsuya’s chest, curling an arm around his waist.

_“Ahh,”_ Natsuya hissed, flinching at the contact as his stomach twisted in knots. He clenched his fists and jerked his hips backwards, terrified that Ikuya would inch even closer and accidentally discover just how turned on he was. There was no way he could sleep like this. As soon as Ikuya was asleep, he’d have to make for the bathroom and jerk himself off. He was deeply regretting not doing so earlier that evening.

“Sorry,” Ikuya said. “You okay?”

“Yeah,” Natsuya replied, clearing his throat. “Just, um, wouldn’t you rather turn around? That’s how you used to like to sleep, right?”

“You remember?” Ikuya asked with a small, pleased smile that went straight through Natsuya.

Ikuya turned around and Natsuya cautiously came up behind him, pressing his chest against Ikuya’s back and being careful to keep enough distance between their hips so that he wouldn’t accidentally stab him with his erection. He placed a hand on Ikuya’s slim waist and let his fingers curl in the worn fabric of the shirt, feeling tight skin and muscle underneath. Ikuya twitched a little, ticklish and sensitive, and Natsuya just barely forced down the urge to grab him and roll him over, pin him down and run his fingers and mouth all over his body, just to see the way he’d gasp and squirm at the touch. He squeezed his eyes shut and swallowed the thought down.

Ikuya lifted his head off the pillow. “Do you wanna put your arm under, too?” he asked.

“Oh, um. Yeah. Okay.” Natsuya hadn’t expected Ikuya to go that far, but he supposed he wanted a full recreation of their childhood days. He slipped his other arm under Ikuya’s neck and bent it at the elbow to wrap it around his chest, then slipped his other hand down Ikuya’s stomach and up his torso, drawing him in even closer like he remembered Ikuya liked. Ikuya made a small murmuring noise in his throat before shuffling back towards Natsuya with a contented sigh

Natsuya had a faceful of his brother’s soft hair and his lips rested at the back of Ikuya’s neck, where he was practically panting with lust against his warm, soft skin. He was getting dangerously, terrifyingly close to some kind of breaking point, and he was past hiding anything anymore - Ikuya would undoubtedly be able to feel the rapid beating of his heart, hear the shakiness to his breath and feel the way his fingers trembled as they clutched at Ikuya’s shirt. If he shuffled back any more, he’d be able to feel Natusya’s undeniable arousal. The thought both terrified and excited him. He pushed his face into his brother’s neck and breathed in deep, the beginnings of a moan escaping his throat on the exhale before he managed to choke it out.

He was so, _so_ close to getting everything he wanted, it was right here in his arms, in his _bed,_ and all he had to do was go ahead and take it. How would Ikuya react if he kissed him right now? If he bridged that last bit of distance between them and rutted against him, hungry and desperate? If he reached down and touched him with shaking but practiced fingers, taking him in hand and making him feel that same curdling mix of incredible pleasure with disgusted, guilty self-loathing that Natsuya taken to bed with him the last few years? Would Ikuya react to it the same way he did, arms open and welcoming to his own degeneration?

“Aniki?” Ikuya said, breaking the silence. “You’re shaking. Are you okay?”

Natsuya grunted and leaned into him more, mouth hovering above Ikuya’s neck, ready to bite in and pin him down. He was hanging on by a thread, and he could feel it about to snap. “Not -- _hah --_ not really, Ikuya. I’m sorry.”

“What’s wrong?” Ikuya began, but before the words had fully left his mouth they were interrupted with a squeaking gasp as Natsuya’s lips and tongue placed a wet, lingering kiss on his neck. He froze in place, tried to whimper something that got caught in his throat, but before he could recover enough to speak properly Natsuya had moved up his neck and kissed him again, teeth nipping at the skin and a long-suppressed groan finally working its way out of his throat.

Ikuya squirmed in his arms and gasped at each press of lips, each swipe of his tongue. “Ahh -- _ahh -- aniki?”_

Ikuya kept his hold on his brother firm and authoritative as he worked a trail of kisses up his neck. “I’m sorry, Ikuya,” he whispered when he reached his brother’s ear. “This is why I had to push you away - I couldn’t stop thinking about -- wanting to --” He gasped, trying to find the right words. “I had to protect you, Ikuya, from myself.”

_“Aniki,”_ Ikuya repeated desperately. He gripped onto Natuysa’s hands where they held tight around his chest, but instead of trying to pull them off, only squeezed them tighter into his chest. His legs kicked out at nothing, squirming and writhing at every press of Natsuya’s mouth on his skin.

Natusya sucked on his ear, taking in his whimpering moans and gasping breath. He could almost believe that Ikuya was enjoying this, too, if the idea didn’t seem so absurd.

“I’m sorry, Ikuya. You must think your big brother’s really disgusting, huh?” he said, illustrating his point with a swipe of his tongue at the base of Ikuya’s jaw.

“Nnngg -- no, aniki,” Ikuya replied through gasping breaths. “I don’t -- _ahh -_ \- I don’t think that.”

“You don’t?” Natsuya lifted his head slightly to look down at his brother’s face. Even in the dim light, he could tell his cheeks were flushed bright red, and his lips were wet and swollen from being bitten and sucked between his teeth.

_“Fuck,”_ he whispered. “Fuck, Ikuya, you have no idea what you’re doing to me.” He spread his fingers out and found Ikuya’s nipples under his shirt, already raised and hardened, and gave them a teasing pull. Ikuya cried out and arched his back, his ass pressing against Natsuya’s crotch.

Natsuya moaned and jerked his hips forward on reflex, rubbing his swollen, neglected cock against the soft cushions of Ikuya’s ass finally, feeling the cooling wetness of precome that had already soaked into his underwear. He bit down on Ikuya’s shoulder and squeezed his eyes shut as he moaned and rutted against him, slow and hard. Ikuya pushed back to meet his thrusts with neediness.

“Ikuya, you -- _fuck_ \-- you need -- need to tell me to stop. Tell me to stop and I -- _ngghh --_ I will. But, otherwise I --”

“Don’t,” Ikuya gasped. “Don’t stop, aniki, please. I just -- _ahh_ \-- all I want is to -- to be with you again. If this is what you want to do with me then -- then I want to do it too. Please, just -- _hah! --_ just don’t push me away again.”

“Ikuya,” Natsuya whispered, hips still rolling in slow synchronization with his brother. He raised one hand to Ikuya’s throat and found his jaw with his fingertips, tiling his face up towards him until they could look each other in the eyes. Ikuya stared up at him with an awed, pleading look that took Natsuya’s breath away. “I won’t,” he promised, and leaned down to taste him.

Natsuya pushed his tongue into Ikuya’s mouth with a rolling lick and sealed it in with his lips, locking their mouths together like they were made for it. Ikuya gave a muffled groan and threw his hands around Natuya’s neck, fingers twisting in his hair and pulling him down closer. He met Natsuya’s tongue with his own, pliant and willing as he let his older brother lick into him and slide their wet lips together over and over again. He did his best to keep up as Natsuya took the lead, but by the time Natsuya finally pulled his mouth away, Ikuya was panting like he had just run a mile.

Natsuya gazed into his eyes, pupils blown wide and lids heavy, half-closed. Eyes dropping to Ikuya’s incredible mouth, he traced a thumb over his bottom lip, swollen and pink, before moving his attention and his mouth back to Ikuya’s neck. Ikuya moaned openly now, pushing his hips back against Natsuya’s and encouraging him to rut against him harder as Natsuya sucked and nibbled gently on his skin, dizzy from the sounds Ikuya made. He rubbed his fingers over his nipples, drawing an almost pained cry from Ikuya’s throat when he pinched them gently. Ikuya reached behind him and dug his fingernails into Natsuya’s hip, urgently trying to pull him in closer while his other hand found one of Natsuya’s and twined his fingers over the back, squeezing his palm down on Natsuya’s knuckles as Natsuya continued to twist and pull at his chest.

Natsuya took a moment to catch his breath, peeling the blankets back to admire the way Ikuya keep pushing his hips back against him again and again. He could probably sit back and let his brother do all the work, if he wanted. The thought almost made him laugh in disbelief.

“You really are a good boy, aren’t you Ikuya?” he murmured, lips hovering over Ikuya’s ear with a dangerous smile. “So good for your big brother.”

Ikuya gave a loud moan and nodded his head fervently.

Natsuya trailed one hand down Ikuya’s torso and slipped it under his shirt, spreading his palm and fingertips flat against his stomach. Ikuya yelped and his muscles contracted reflexively, but Natsuya held him tight with his other arm around his chest and continued to pull his shirt higher until it was gathered up by his collarbone.

Ikuya’s skin was warm and silky soft as it pressed up against Natsuya’s chest, and the feeling of their bare bodies sliding over one another was incredible. Natsuya sucked a mark into Ikuya’s shoulder and looked down at his exposed chest, flat and lightly defined by lean muscle. He wrapped a leg around Ikuya’s ankles and pulled his legs down, stretching his lean, delicate body out before him and exposing the hard bulge of his cock through his underwear. Natsuya groaned and swore under his breath at the sight of it. He watched as if hypnotized as his own hands glided up and down Ikuya’s body, from the curve of his throat down to the elastic band of his underwear.

“You’re so beautiful, baby,” Natsuya murmured into Ikuya’s ear, teasing his teeth along the edge. “God, you’re so hot. I can’t keep my eyes off you, you know? Have you noticed how I stare at you?”  
  
Ikuya nodded with a whimper.

“Yeah? You noticed and you still decided to climb into my bed wearing nothing but one of my tee-shirts? Fuck, did you know what that was going to do to me? Maybe you’ve been trying to seduce me all this time.”

Ikuya shook his head. “Nn -- no, aniki, I -- _nnngg.”_

“It’s okay, baby,” Natsuya whispered teasingly. “We can be perverted together, now. You like this, right?” He wrapped an arm around Ikuya’s waist and thrust against him harder, rutting his cock right between Ikuya’s ass cheeks.

_“Mmm --_ y-yeah. I like it. I -- _hah! --_ I like it, aniki. _Ahh!”_

“Good boy, Ikuya,” Natsuya murmured, and he slowly slipped his fingertips under the elastic of Ikuya’s underwear and peeled it back, exposing his hard, flushed cock. It twitched and bobbed as the cool air hit it, a trail of precome attached to his underwear breaking off and smearing down along his thigh. Ikuya trembled and groaned, gripping his blunt nails into Natsuya’s skin.

“Such a good boy. You make your big brother so proud,” he said, and Ikuya went wild as Natsuya tugged the elastic right down off his ass and pressed his still clothed cock between Ikuya’s cheeks, pressing heavy and blunt against his entrance. His hips writhed and shook as he all but shouted a moan, but Natsuya kept him pressed close to him with a leg still around his ankles and a hand at his hip.

Natsuya slid his hand slowly to Ikuya’s cock and wrapped his palm around the head, causing Ikuya to jolt with a hiss of breath. He swirled precome around the tip of his cock and teased more out with a twisting motion of his wrist. “That good, baby?” he murmured.

_“Mmm,_ aniki,” Ikuya moaned. “Aniki, aniki -- _ahh!”_

Natsuya groaned and sped up the pace of his trusts as Ikuya called out his name over and over, more and more desperate each time. He wrapped his hand around the full girth of his cock and pumped over his base with a tight grip and quick rhythm.

“Aniki, aniki -- _ahh! -- aniki!”_

“Are you going to come already, baby?” Natsuya asked, eyes closed as he felt his own orgasm building, each thrust into Ikuya’s ass cheeks and every cry of his name from Ikuya’s lips adding fuel to the raging fire. He was vaguely aware of Ikuya nodding as he gave a particularly desperate moan. “Then be a good boy, Ikuya, and come for me,” he panted.

_“Ahh -- oh, fuck -- aniki!”_

Ikuya’s whole body shuddered as his cock pulsed in Natsuya’s hand, spilling come up his stomach and onto the bed sheets. Natsuya groaned his brother’s name and wrapped himself around him tight as he followed, come making a mess of his underwear and seeping through the fabric where he rutted jerkily against Ikuya’s entrance.

“Ikuya,” he gasped, heart pounding as he rode out the high. _“Fuck,_ Ikuya.”

He cupped a hand to Ikuya’s cheek and found his mouth with urgency, pushing his tongue inside and sliding their lips together deep and slow, swallowing down each other’s moans until they were both so exhausted and blissed out they could barely kiss back.

Natsuya sank back down to the pillow and pulled Ikuya to his chest, tracing fingers lazily over his collarbone and sighing happily into his hair.

“Aniki…” Ikuya mumbled, sounding 90% of the way to sleep already.

Natsuya smiled and nuzzled his nose against the back of Ikuya’s neck, absently thinking that this was the first time he’d gotten off to his brother without feeling guilty or disgusted at himself afterwards, which was ironic considering what he had just done was worse than anything before. But Ikuya seemed so happy and relaxed - more so than he had been in years - that Natsuya couldn’t find it in himself to even try to feel bad about it.

When his brother’s breathing fell slow with sleep, Natsuya carefully untangled himself from him and slipped out of bed, disposing of his underwear in a clothes basket and sneaking out to use the bathroom. He looked at his reflection in the mirror - eyes heavy and relaxed with hazy satisfaction, lips pink and plush from use. There was a pleased, almost smug smile on his mouth that he found he couldn’t get rid of even if he tried. He splashed cold water on his cheeks and pinched himself a couple of times, just to test that this was real. He could barely believe it, but apparently it was. Still grinning, he grabbed a couple of towels and took them back to the bedroom with him.

Slipping back under the covers, Natsuya wiped come off the bed and Ikuya’s stomach with the corner of a towel before throwing it to the floor and curling back to spoon around him.

Ikuya stirred awake and gave a mumbled “thanks,” as he pulled Natsuya’s arms tight around him, wriggling his hips back to get comfortable.

“Ikuya,” Natsuya whispered, stroking his hair with gentle fingers. “Are you okay? You don’t regret it?”

Ikuya rolled over to his other side to face him and buried his face up against Natsuya’s neck, twirling their legs together and snaking an arm around his back. “I don’t,” he said, shaking his head. “But... we’ll be in trouble if someone finds out.”

“Big trouble,” Natsuya agreed, rubbing a hand gently up and down Ikuya’s spine.

“What should we do?”

“Well, we’ll just have to make sure we don’t get caught, won’t we?” Nastuya said, smiling into the locks of Ikuya’s hair tickling at his mouth. “But don’t worry, big brother will keep you safe. Unless you’d rather we stop, of course.”

Ikuya shook his head, gripping his arms around Natsuya possessively. “No way.”

Natsuya chuckled and patted Ikuya’s hair. “Good boy.”

Ikuya shivered in his arms, stretching with a quiet moan.

“You really like that one, huh?” Natsuya teased, pulling his head back gently with a fistful of hair and nibbling at his bottom lip playfully, working it between his teeth and sucking it into his mouth. Ikuya moaned in agreement.

With a hand gripping each of Ikuya’s hips, Natsuya rolled them over so he was flat on his back with Ikuya straddling him. He pulled his brother down flush against his chest and sought out his lips again, pushing them open with his own and painting the inside of his mouth with his tongue until Ikuya was a panting mess, moaning and rutting his growing erection against Natsuya with an unpracticed but desperate jerk of his hips.

Natsuya pulled their lips apart and looked up at his baby brother, breathless and heavy-lidded from arousal. He grinned at Ikuya dotingly, amber eyes gleaming at the matching pair above him. “Ready for more?”

**Author's Note:**

> So I finally watched Starting Days in preparation for Free season 3 and... welp... this pairing really grabbed me by the throat but there's like 3 fics in the tag, rip. Sometimes you've just gotta come through for yourself and write the smut that you want to see in the world! 
> 
> Kudos to this ship for getting me to actually finish writing something for the first time in literally years. I have more ideas for these two but unsure if I'll write them yet or focus on some other pairings (Free or otherwise), but if you wanna see more then please comment! I will probably write more if enough people are interested <3


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